With the increasing demands of high-definition (HD) displays and other applications, and with the widespread usage of smart phones and tablets, next generation WLANs capable of transmission at higher data rates in the millimeter wave (mmWave) bands are needed. The IEEE 802.11ad (directional multi-gigabit (DMG)) specification provides a WLAN technique that operates in the globally unlicensed 60 GHz band, e.g., 57-71 GHz. Next generation 60 GHz WLANs (EDMG) such as IEEE 802.11ay (evolved DMG (EDMG)) are currently being developed that will be capable of even higher performance than 802.11ad, and will also provide backward compatibility and coexistence with 802.11ad.
Training sequences typically take the form of sequences or waveforms known to both the transmitter and the receiver. Training sequences are used mainly for the purpose of synchronization and channel estimation, and may also carry other information (e.g., signaling or user information, etc.) that can be detected, typically blindly, on the receiver side. The IEEE 802.11ad specification defines a frame structure that includes two fields for training sequences, namely a short training field (STF) and a channel estimation field (CEF). The channel estimation field (CEF) is used for finer synchronization.
It would be useful to provide improved training sequences that can mitigate against co-channel interference in the context of next generation mmWave networks such as IEEE 802.11ay.